Method and apparatus utilizing a rotating electromagnetic field for separating particulate material having different magnetic susceptibilities

ABSTRACT

Crushed iron ore is introduced into a rotating electromagnetic field. The tailings, which possess little or no magnetic susceptibility, drop downwardly and are gravitationally removed. The concentrate, having a high degree of magnetic susceptibility, is carried by the field for almost a complete revolution. The middlings, on the other hand, have a degree of susceptibility less than the concentrate, and are accelerated with the concentrate only until a sufficient amount of centrifugal force is developed to throw the middlings outwardly to thus separate them from the concentrate.

United States Patent 3,684,090 Kilbride I [451 Aug. 15, 1972 [S4] METHODAND APPARATUS I FOREIGN PATENTS OR APPLICATIONS UTILIZING A ROTATING52,292 9/1889 Germany ..209/219 ELECTROMAGNETIC FIELD FOR 125,206 3/1959U.S.S. R. ....209/227 SEPARATING PARTICULATE 298,617 4/1930 Germany..209I227 MATERIAL HAVING DIFFERENT 433,6l6 8/ 1935 Great Britain..209/219 MAGNETIC SUSCEPTIBILITIES 534,317 12/1956 Canada ..209/219lnvemor: J R. Kilbride, 705 Gram 160,430 4/1941 Austria ..209/223 REveleth, Minn. 55734 OTHER PUBLICATIONS [22] Filed: Dec. 10, 1969 R14059, Bu of Mines, I216. 10, I8 & 19, Man, 1947 [21] Appl No: 883,909Copy in GR 177 & Sc. L b.

Primary Examiner-Frank Lutter [52] US. Cl. ..209/214, 209/223, 209/227Assistant Examiner-Robert Halper [51] Int. Cl. ..B03c l/14, B03c 1/24Attorney-Dugger, Peterson, Johnson & Westman [58] Field of Search..209/218, 219, 223, 227, 214,

209/212, 220; 55/3; 210/222, 223 [57] ABSTRACT Crushed iron ore isintroduced into a rotating elec- [56] References cued tromagnetic field.The tailings, which possess little or UNITED STATES PATENTS no magneticsusceptibility, drop downwardly and are gravitationally removed. Theconcentrate, having a 1,529,970 3/1925 Ulll'lCk ..209/219 X high degreeof magnetic Susceptibility, is carried by 1,564,731 I2/ 1925 I Weatherby..209I227 X the field for almost a complete revolution The R0th. .t

on other hand, hav a degree of uscep 2,979,202 4/1961 Orbellanl -209/223R tibility less than the concentrate, and are accelerated 3,327,8526/1967 Mortsell ..209/219 with the concentrate only until a sufficientamount f 1,417,189 5/ 1972 McCarthy centrifugal force is developed tothrow the middlings outwardly to' thus separate them from theconcentrate.

I 24 Claims, 7 Drawing Figures CRUSHED o mg 2 5 0 0 Ill 1W ""H'I'I I 54i t /Z all a I. i

PATENTEDAUG 15 m2 SHEET 1 OF 3 CRUSHED ORE 34 FlELD INVENTOR. JAMES R.KILBRIDE i l )7 l6 Arfo fneys PATENTEDAUB 15 1912 SHEET 2 [IF 3 FIG 4 3FIELD CONCENTRATE INVENTOR.

JAMES R Kl LBR IDE TAILINGS MIDDLINGS BY m,%wfm

Horn eys METHOD AND APPARATUS UTILIZING A ROTATING ELECTROMAGNETIC FIELDFOR SEPARATING PARTICULATE MATERIAL BACKGROUND OF THE INVENTION 1. Fieldof the Invention This invention relates generally to electromagneticseparation, and pertains more particularly to a method and apparatusutilizing centrifugal force developed from a rotating electromagneticfield to remove certain particles having an intermediate degree ofmagnetic susceptibility.

2. Description of the Prior Art Apparatus and methods have heretoforebeen devised which employ either a rotating electromagnetic field or arectilinearly traveling field for separating crushed iron ore into whatis commonly referred to as concentrate, middlings and tailings. Oneprior art separator is embodied in US Pat. No. 1,605,117 granted Nov. 2,1926 to Mitsuo Koizumi titled Ore Separator of AlternateCurrent-Electromagnet. The alluded to patent uses a number of spiralbafiles to effect the separation. Each magnetic particle, however, musttravel around the stator as may times as there are baffles, resulting inonly a limited capacity and also a rather inefficient method ofobtaining the separation inasmuch as a considerable amount of frictionis present by reason of the fact that the particles have to roll alongthe battles and a sufficiently strong rotating electromagnetic fieldmust be resorted to in order to move the particles. Also, the apparatusconstituting the patented separator is quite complex and costly tobuild.

Another prior art attempt is to be found in the disclosure of U.S. Pat.No. 1,564,731, granted Dec. 8, 1925 to Joseph Weatherby titled Methodand Apparatus for Separating Ore Particles. The invention thereindescribed relates to a separator employing a rectilinearly movingelectromagnetic field, which is even more dissimilar from the instantinvention than is the Koizumi invention, but the second-mentioned patentis of interest because it goes into considerable detail with respect tothe utilization of polyphase alternating current for producing orgenerating the traveling field. Actually, reference should be made tothis particular patent for an understanding of the manner in which thefield herein utilized is generated should there be the need for anadditional technical explanation.

SUMMARY OF THE INVENTION Broadly, the invention has for an object theseparation of material composed of particles having different magneticsusceptibilities: (1) those below a given level of susceptibility, (2)those having a relatively high degree of susceptibility, and (3) thosehaving a lesser susceptibility but still above the given level.

A more specific object of the present invention is to provide animproved iron ore separator and a method of separating the orecomponents which employs not only an electromagnetic field but utilizesthe centrifugal force developed thereby in achieving the separation.More specifically, the invention has for an aim the provision of acentrally disposed stator that generates a rotating magnetic field anduse is made of the field for accelerating both the concentrate and themiddling, the

middlings developing a sufficient amount of centrifugal force so thatthey are flung or thrown outwardly from the stator. In this way themiddlings are removed, whereas the concentrate remains in the rotatingfield and is subsequently withdrawn, although still within onerevolution of the rotating field. Stated somewhat diflerently, therelatively weak magnetic particles in the ore are separated bycentrifugal force, being thrown outwardly from the concentrate whichremains in the field until physically deflected therefrom.

More specifically, an aim of the invention is to pro vide av separatorthat will concentrate magnetic taconite with a relatively low magneticfield intensity, although the separator can also be used to concentrateany mineral having various degrees of susceptibility.

Another object of the invention is to produce an excellent mixing actionduring the introduction of the crushed ore which liberates a highpercentage of unwanted impurities at the outset, the mixing actioncontinuing as far as the middlings and concentrate are concemed untilthe middlings are flung outwardly by the centrifugal force that results.

An additional object of this invention is to make the magneticseparations in a wet or dry atmosphere, that is the material can be madefluid in either a gaseous or liquid state.

Another object of the invention is to provide a separator that willrequire fewer stages of separation, actually a good quality separationlbeing practical with only one pass, although additional stages can beresorted to, especially where a high level of purity is desired in theconcentrate or where the middlings might very well contain valuablemagnetic particles that should be removed through the agency ofsubsequent staging.

A still further object of the invention is to provide a method andapparatus of the foregoing character that can be easily adapted to largescale operations.

Still further, an object is to provide apparatus that is relativelysimple, particularly as contrasted with separators now in widespread usethat involve moving parts. Also, concommitant with the simplicity of theequipment, there is the added advantage of low maintenance costs.

Yet another object of the invention is to provide a separator that canbe readily designed to separate a given size of particulate material,the design lending itself to easy selection or variation of fieldstrength, that is the gauss rating thereof, and also with respect to thespeed at which the field rotates.

Another object of the invention is to provide a separation in which thedegree or quality of separation for the various classes of componentscan be adjusted, an appropriate baffle or splitter being employed.

Still an additional object of the invention is to provide a separatorthat will be highly efficient in its separating action, and an aim ofthe invention is to provide a stator having a design that maximizes thematerial flow through the separator for a given amount of power.

Briefly, the present invention envisages the production of a rotatingelectromagnetic field, the crushed iron ore being introduced at a firstradial location with respect to the stator generating the field. Thetailings fall immediately downwardly and are removed. The

concentrate and the middlings, however, are accelerated from the firstradial location and near the end of one rotation of the field, provisionis made for removing the concentrate. The middlings, though, are removedas soon as they have developed a sufficient amount of centrifugal forceto be flung out of the rotating electromagnetic field. In this way,there are three distinct classes of separation. Furthermore, the qualityof separation is capable of being controlled or adjusted.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of one formthe apparatus exemplifying my invention may assume, most of the topcover of the casing being removed so as to expose to view thehorizontally oriented liner of the stator that provides the rotatingelectromagnetic field;

FIG. 2 is a vertical sectional view taken in the direction of line 2--2of FIG. I with a representative ore sampling added for the purpose ofillustrating to better advantagehow the separation occurs;

FIG. 3 is a flat or developed view of a stator resembling the preferredform employed in the embodiment of FIGS. 1 and 2, and also FIGS. 4-7,the view being diagrammatic inasmuch as the coil and slot configurationdoes not correspond precisely to the more effective tapered tootharrangement depicted in FIGS. 2, 5 and 7;

FIG. 4 is a top plan view corresponding to FIG. 1 but illustrating adifferent embodiment that the invention may assume, although employing ahorizontally arranged stator as in FIGS. 1 and 2;

FIG. 5 is a sectional view taken in the direction of line 5-5 of FIG. 4,a sampling of ore being depicted within the apparatus for the purpose ofillustrating the method by which separation occurs in this instance;

FIG. 6 is a side elevational view of still a difi'erent embodiment ofthe invention, this modification utilizing a vertically oriented stator,and

FIG. 7 is a sectional view taken in the direction of line 77 of FIG. 6for the purpose of revealing the internal construction of thisparticular modification of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to theembodiment depicted in FIGS. 1 and 2, it will be perceived that theseparator there illustrated has been denoted in its entirety by thereference numeral 10. The separator 10 includes a casing or housing 12having a bottom 14, end walls 16, 18, side walls 20, 22, and a top cover24, the enclosure forming a chamber which has been generally labeled Ofextreme importance in the practicing of the instant invention is thestator indicated by the reference numeral 30. The stator 30 comprises acylindrical shell 32 of non-magnetic material, such as stainless steelof suitable wear-resistance plastic. The shell 32 has its opposite endssecured, as by welding (when metal), to the side walls and 22 atlocations 33 and 35. The stator 30 has a core 34 comprised of a numberof thin laminations labeled 36 which should be of high grade electricalsteel, as is conventional with larninations utilized in various types ofmotors in order to minimize hysteresis and eddy current losses. As canbe seen from FIG. 2,

each lamination is formed with a series of radially projecting teeth 38that taper or converge to virtually a point at their outer ends, theextremities having been given the reference numeral 40. In this way, theslots, formed between the angularly spaced teeth due to the stacking ofthe laminations 36, are wider interjacent the shell 32 than at the baseor root of the various teeth. It will be appreciated, especially as thedescription progresses, that the flow of material through the separatoris maximized or increased by virtue of the tooth configuration hereinemployed, because the stator 30 functions as a polyphase electromagnetand in this way an optimum amount of flux is provided through the orematerial undergoing separation. More specifically, there is a minimumamount of leakage flux that occurs between the teeth forming the slotsowing to the tapered tooth configuration.

Continuing with the description of the stator 30, it will be appreciatedthat the slots formed between the various teeth 38 contain therein thecoils or windings identified by the reference numeral 42. The way inwhich the coils 42 are wound and the manner in which they are energizedby a three-phase source of alternating current can be understood, it isbelieved, from FIG. 3 where a developed or flat simulation of thewinding arrangement appears. Actually, FIG. 3 has been taken from thepreviously mentioned Weatherby US. Pat. No. 1,564,731, which, as alreadyindicated, goes into considerable detail concerning the production orgeneration of a three-phase electromagnetic field. It is to berecognized that thecore labeled 34a (the suffix a distinguishing theelements from their FIG. 2 counterparts) in FIG. 3 is not preciselyidentical to the core 34 of FIG. 2, mainly because the variousIaminations indicated by the reference numeral 36a do not have thepointed teeth formed thereon. It would be rather difficult to illustratethe winding pattern if the pointed teeth were actually pictured in FIGS.Accordingly, the coils or windings have been given the reference numeral42a and it will be seen that they are connected to conductors 44 whichare in turn supplied with threephase power, the phase relationshiphaving been indicated by the letters A, B and C. The source of power hasnot been shown, but it is to be appreciated that the source may have incircuit therewith means for varying the voltage and hence the powersupplied via the conductors 44. In actual practice, a three-phase Variachas been utilized for the purpose of controlling the voltage and in turnthe amount of current flow to adjust the strength of the resultingrotating electromagnetic field. As will presently be understood, thephysical configuration of the housing 12 requires that the field rotatein the direction of the arrow 46 applied to FIG. 2.

Associated with the end wall 18 is a chute 48 having a horizontal slotor inlet opening 50 disposed at a first radial direction (3 oclockposition) with respect to the stator 30. A fixed baffle 52 extendsdownwardly from the lower edge of the inlet opening 50. Spaced somewhatabove the upper end of the chute 48 is a feeder 54 which includes anendless belt 56, only a portion thereof having been pictured. The ironore has been indicated generally by the reference numeral 58 and it willbe appreciated that the quality or iron con tent of the ore 58 will varyconsiderably. Actually, taconite, which is a rather low grade ore, willcontain a wardly (that is, counterclockwise), the tailings, whichconstitute the non-magnetic material, will move gravitationallydownwardly along the baflle 62 into a region indicated by the referencenumeral 60, the left side of the region 60 being defined by a fixedlydisposed barrier or baffle plate 62 that extends between the side walls20, 22. Hence, the tailings are directed downwardly into an outlet 64via which they are removed from the apparatus.

On the other hand, the remainder of the ore 58,

which contains both the middlings and concentrate,

will be introduced directly into the rotating field and will beaccelerated upwardly and around the circumference of the stator 30 owingto the magnetic influence exerted by the moving field. Due to the factthat the middlings have a magnetic susceptibility that will be of anintermediate value, they will move along with the concentrate but willbe subjected to centrifugal actionthat flings or throws the middlingsoutwardly, whereas the concentrate continues to be carried in theelectromagnetic field and will complete a considerable portion of onerevolution of the field. More specifically, the concentrate will becarried to a region labeled 66 which is approximately 270 from thelocation at which the ore enters through the opening 50, this region 66being just to the left of the fixed barrier 62 which literally scraps ordeflects the concentrate from the liner 32 so that it then fallsdownwardly through the region 66 into an outlet 68 where it is removedfrom the apparatus. The region 66 is further defined by an angularlyadjustable baffle or splitter vane 70, being pivotally mounted at 72 and74 as can be seen in FIG. 1. Although provision would normally be madefor holding the splitter 70 in an adjusted position, a handle 76 willserve the purpose of illustrating that the vane 70 can be swung eitherto the left or right with respect to the vertical position in which itis pictured in FIG. 2. To the left of the vane 70 is a region 78 thataccepts the middlings that are flung outwardly by centrifugal force. Inother words, the middlings, being of intermediate magneticsusceptibility, are no longer retained in the rotating field when theyreach a given speed and the region 78 serves to direct the middlingsdownwardly through an outlet 80.

Due to the small scale of the drawing, it would be extremely difficultto depict the particles constituting the crushed ore 58 in the propersize relationship, especially since a considerable amount of the crushedore will be of fine size, say on the other of 500 mesh and varying to alarger size of approximately 8 mesh. At any rate, it might be of help toindicate the concentrate by solid black circles, the middlings bypartially blackened circles and the tailings by undarkened or whitecircles. To further assist in understanding the separation procedure,the concentrate has been denoted by the reference character 58,;, themiddlings by the reference character 58 and the tailings by thereference I character 58,.

Having presented the foregoing description, which to a large degreecontains an adequate description of the operational sequence, only abrief resume will be given as to what occurs ineffecting the desiredseparation. In this regard, the crushed ore 58 is introduced into theelectromagnetic field via the slot-like opening 50, being carried in therotating electromagnetic field and are progressively accelerated. Theacceleration results in the middlings 58 being subjected to a sufficientamount of centrifugal forceso that they are flung outwardly from theconcentrate 58 the middlings 58 falling downwardly into the outlet 80and the concentrate 58 leaving via the outlet 68. Thus, the ore 58 isintroduced into the-electromagnetic field at one radial location and theconcentrate is removed at a radial locationapproximately it (270) of arevolution from the point at which the ore is introduced, the middlings58 being removed during an intermediate segment of the rotative travelof the concentrate 58 Recapitulating, agiven level of magneticsusceptibility may be selected, with the field intensity or gauss ratingadjusted or determined for the particular level, the

particles having less than this level will be removed gravitationallythrough the outlet 64 because they will be virtually unaffected by therotating field. These particles would constitute the tailings abovereferred to. Thoseparticleshaving A susceptibility above said level, yetrelatively near thereto are carried along with the particles possessinga relatively high magnetic susceptithey then fall through the outlet 68.Those particles having a lesser propensity for magnetization, that isthose nearer the given susceptibility level and which have been calledmiddlings, are the onesthatare flung or thrown from the field so thatthey fall through the outlet 80.

Passing now to a description of the embodiment illustrated in FIGS. 4and 5, this embodiment being labeled generally by the reference numeral1 10, it is believed of help to explain that some of the parts orcomponents are virtually identical with those described inconjunctionwith the embodiment identified by'the numeral 10. Therefore,where the parts are the same, identical reference numerals have beenutilized; where theparts have a general resemblance but-differ in someaspect, then the order of the numerical designation has been raised byonehundred.

It will be initially of benefit to point out that the rotatingelectromagnetic field rotates in a direction opposite to that describedin connection with the apparatus 10. Thus, the arrow 146 indicates thespecific direction.

The crushed ore 58 is fed into a chute 148, and by means of a pair oflaterally spaced pipes or conduits 149the-ore is fed downwardly into theinterior 126 of the separator .110. A curved baffle 151, which has itsends fixedly attached to the sidewalls and 122, directs the ore inwardlyinto the intense rotating field.

However, the tailings 5S fall gravitationally downwardly, whereas theconcentrate 58 and the middlings 58 continue with the rotating field.When the acceleration of the middlings 58 reaches a sufiicient value,they are flung by centrifugal force outwardly and are removed. On theother hand, the concentrate 58 continues for practically an entirerevolution (almost 360), actually farther than that in the separator 10.In this instance, a fixed baffle 162 deflects or skims off theconcentrate so that it then falls gravitationally downwardly through theoutlet 164 via which it is removed from the apparatus.

By reason of the adjustable splitter vane 170, the amount of ore 58passing therebeyond can be controlled. Thus, if only a small portion ofthe concentrate 58 that is a superior quality concentrate, is to bepermitted to pass, the vane 170 can be adjusted so that it assumes theposition in which it appears in FIG. 5, whereas it can be rotatedclockwise to allow more particulate material to pass, that is a somewhatless pure concentrate to be realized. The embodiment pictured in FIGS. 4and 5 will permit an accurate determination of the grade that themiddlings is to constitute.

FIG. 6 and FIG. 7 represent still a third embodiment, the separator inFIGS. 6 and 7 having been denoted by the reference numeral 210. In thissituation, the casing 212 is cylindrical, being composed of a singlewall 220. Instead of the flat bottom, the bottom 214 is conical and theoutlet 264 for the tailings 58 is centrally located. The outlet for themiddlings 58 has been given the reference numeral 280.

The inlet chute 248 receives the crushed ore 58 and it is directedgravitationally downwardly onto a sloping diverter or fixed baffle 252.The baffle 252 extends virtually to the line 77 representing the planein which FIG. 7 is taken. Actually, the baffle 252 can extend the fullheight of the cylindrical housing 212 but this is not necessary becausethe tailings 58 fall gravitationally downwardly and strike the slopingsides of the conical bottom 214 and are immediately discharged via theoutlet 264. The field, which is rotating in the direction of the arrow246, carries both the concentrate 58 and middlings 58 will ultimately beflung outwardly due to the centrifugal action that occurs. Thus, a flatplate 265 is located just above the conical bottom 214; the middlings 58will fall on to this particular plate and will exit via the outlet 280.

On the other hand, the concentrate 58 will continue and will literallybe scraped off or deflected by the fixed baffle 262 so that theconcentrate 58 leaves through the outlet 264. An adjustable splittervane 270 having a handle 276 can be positioned so as to determine thepercentage of middlings 58,, that are removed from the concentrate 58Thus, if the middlings 58 are to contain some concentrate, in effectmaking the concentrate 58 of higher grade, the vane 270 can be moved sothat it resides near the liner 32 of the stator 30. When The percentageof middlings 58 is to be reduced, then it will be moved outwardly awayfrom the liner 32, being nearer the outlet 280. In this way, as with theother embodiments, the grade of separation can be controlled.

lclaim:

l. A method of separating material composed of particles having severaldifferent magnetic susceptibilities,

said material including first particles having a. magneticsusceptibility below a given level, and second and third particleshaving magnetic susceptibilities above said level, said third particleshaving a higher susceptibility than said second particles, the methodcomprising the steps of producing a rotating magnetic field of uniformstrength, introducing the material to be separated into the field atfirst location so that the first particles having a magneticsusceptibility below said given level flow gravitationally downwardlyand said second and third particles having a susceptibility above saidgiven level are accelerated entirely by said field to the extent thatthe second particles possessing a magnetic susceptibility nearer saidgiven level are thrown outwardly due to centrifugal force developedsolely by saidrotating field and are thereby separated from the thirdparticles having a higher susceptibility, and removing said highersusceptibility third particles from said field at a second locationprior to the completion of a full revolution of said rotating field andprior to reaching said first loca tion where the material to beseparated is introduced, whereby said first particles are initiallyseparated by gravity from said second and third particles, and saidsecond particles are subsequently centrifugally separated from saidthird particles at a third location between said first and secondlocations.

2. The method set forth in claim 1 in which said field rotates about asubstantially horizontal axis.

3. The method set forth in claim 2 in which said first location at whichthe material is introduced is spaced from said axis in a generallyhorizontal direction.

4. The method set forth in claim 3 in which said first location isdisposed where the field is moving upwardly and said third particleshaving a higher magnetic susceptibility are removed at a location spacedangularly approximately 270 from said first location.

5. The method set forth in claim 3 in which said first location isdisposed where the field is moving downwardly and said third particleshaving a higher magnetic susceptibility are removed at a location spacedapproximately 360 from said first location.

6. The method set forth in claim 1 in which said field rotates about asubstantially vertical axis.

7. The methods set forth in claim 6 in which said first location isdisposed radially outward from said axis and at an elevation above themiddle of said axis.

8. The method set forth in claim 3 in which the location for removingsaid first particles having a lesser magnetic susceptibility is beneathsaid first location.

9. Apparatus for separating material composed of particles havingdifferent magnetic susceptibilitiescomprising a stator including astationary non-magnetic shell having a generally cylindrical outersurface and a generally cylindrical inner surface and a plurality ofpolyphase windings fixedly disposed within said shell in an adjacentrelationship with the said inner surface thereof, said windingsgenerating a rotating electromagnetic field that progressescircumferentially therearound, means for introducing said material intosaid field at one radial location so that particles having a magneticsusceptibility less than a given level fall gravitationally out of saidfield and the particles having a magnetic susceptibility above saidgiven level are accelerated exclusively by said field to the extent thatthose particles possessing a magnetic susceptibility nearer said givenlevel are thrown outwardly away from the outer surface of said shell duesolely to centrifugal force developed only by said rotating field andthereby separated from those particles having a higher susceptibilitywhich continue in a proximal relationship to said outer surface due tosaid rotating field, means for collecting said centrifugally separatedparticles so that they remain separated from those particles having ahigher susceptibility so that said higher susceptibility particlescontinue in said proximal relationship to said outer surface, and meansextending outwardly from the outer surface of said shell at a locationless than 360 from said one location for deflecting those particleshaving a higher susceptibility which have continued along said outersurface from said field prior to the completion of a full revolution ofsaid field.

10. The apparatus set forth in claim 9 in which said stator is disposedalong a substantially horizontal axis.

11. The apparatus set forth in claim 12 including means having an inletopening disposed generally horizontally at said one location where theelectromagnetic field is moving outwardly, and means located generallybeneath said stator via which those particles having a magneticsusceptibility less than said given level are gravitationally removed.

' 12. The apparatus set forth in claim 11 in which said means fordeflecting said higher susceptibility particles from said field includesa barrier extending angularly from said stator, said means forgravitationally removing these particles having a magneticsusceptibility less than said given level being to one side of saidbarrier, and means to the other side of said barrier for removing theparticles having the highest magnetic susceptibility after beingdeflected by said barrier.

13. The apparatus set forth in claim 12 including an adjustable splittervane for determining the cross sectional area through which the highestmagnetic susceptibility particles pass and thereby the amount thereof.

14. The apparatus set forth in claim 10 including means having an inletopening disposed generally at said one location where theelectromagnetic field is moving downwardly, and means located generallybeneath said stator via which those particles having a magneticsusceptibility less than said given level are gravitationally removed.

15. The apparatus set forth in claim 14 in which said means fordeflecting said high susceptibility particles from said field includes abarrier extending angularly from said stator immediately above said onelocation, and an adjustable splitter vane beneath said stator fordetermining the cross sectional area through which the particles abovesaid given level of susceptibility pass and thereby the amount thereof.

' 16. The apparatus set forth in claim 15 in which said means forremoving those particles having a magnetic susceptibility less than saidgiven level is to one side of said splitter vane and said means forcollecting said centrifugally separated particles is to the other sidethereof.

17. The apparatus set forth in claim 9 in which said stator is disposedalong a substantially vertical axis.

18. The apparatus set forth in claim 17 in which said one location isadjacent the upper end of said stator.

19. Apparatus for separating material composed of particles havingdifferent magretic susceptibilities ill comprising a housing, a statorincluding a stationary non-magnetic shell having a generally cylindricalouter surface and a generally cylindrical inner surface and a pluralityof polyphase windings fixedly disposed within said shell in an adjacentrelationship with the inner surface thereof, said shell being arrangedhorizontally within said housing and said windings generating a rotatingelectromagnetic field that progresses circumferentially therearound,means for introducing the material to be separated into said field atone radially located position so that the particles having a magneticsusceptibility below a given level fall gravitationally toward thebottom of said housing and those particles having a magneticsusceptibility above said given level are carried by said rotatingfield, means located at a second radial position spaced angularly fromsaid first position for deflecting the material'having a high magneticsusceptibility out of said field, first means for collecting thematerial having a magnetic susceptibility nearer said given level whichis thrown outwardly away from the outer surface of said shell bycentrifugal force developed solely from said rotating field, and secondmeans for collecting the material having said high magneticsusceptibility deflected by said deflecting means after said materialhaving a magnetic susceptibility nearer said given level has been thrownoutwardly away from said outer surface due to centrifugal force.

20. The apparatus set forth in claim 1% including a splitter vaneadjustably positionable with respect to said stator so as to causemoreor less concentrate to be removed.

21. The apparatus set forth in claim 20 in which said second collectingmeans includes an outlet in the bottom of said housing via which thematerial having a relatively high magnetic susceptibility is removed andsaid firstcollecting means includes an outlet in the bottom of saidhousing via which the material having a magnetic susceptibility nearersaid given level is removed, and in which said splitter vane ispivotally mounted about a horizontal axis so that its upper edge can beswung to a position nearer said stator to divert more of said materialhaving a magnetic susceptibility nearer said given level into said firstcollecting means and less of the material having a relatively highmagnetic susceptibility into said second collecting means.

22. Apparatus for separating material composed of particles havingdifferent magnetic susceptibilities comprising a housing having abottom, a stator includ ing a stationary non-magnetic shell having agenerally cylindrical outer surface and a generally cylindrical innersurface fixedly disposed in said housing and a plurality of polyphasewindings fixedly disposed within said shell for generating a rotatingelectromagnetic field, the bottom of said housing having a first outletformed therein located beneath said stator via which non-magneticparticles are gravitationally discharged, means for introducing saidmaterial into said housing at a location adjacent said stator so thatthe material enters the field at a relatively high intensity portionthereof whereby the particles having a magnetic susceptibility above agiven level are accelerated entirely by said field to the extent thatthose particles possessing a magnetic susceptibility nearer said givenlevel are thrown outwardly from the outer surface of said shell due tocentrifugal force developed solely by said rotating field, said bottomhaving a second outlet therein laterally offset from said shell viawhich said centrifugally separated particles are removed, a barrierextending across said housing for deflecting those particles having arelatively high magnetic susceptibility from said field, said barrierbeing located a substantial angular distance from the location at whichthe material is introduced into said housing, said bottom having a thirdoutlet opening located near said barrier so that material deflectedthereby which has continued in a proximal relation along said outersurface is removed via said outlet.

23. The apparatus of claim 22 including a splitter vane between saidsecond and third outlet for diverting more of said relatively highmagnetic susceptibility material through said third outlet when movedinto one position and less of said relatively high magneticsusceptibility material when moved into a second position.

24. In apparatus for separating materials composed of particles havingdifferent magnetic susceptibilities, a housing, a stator contained insaid housing comprising a, plurality of stacked laminations, eachlamination having a series of angularly spaced pointed teeth projectingradially outwardly therefrom to form slots between the various angularlyspaced teeth, a plurality of coils disposed in said slots, a nonmagnetic liner encircling the pointed ends of said teeth, wherebypolyphase energization of said coils produces a rotating fieldsufficiently intense so as to carry with it particles having a magneticsusceptibility above a given level and which field will produce asufiicient amount of centrifugal force to throw outwardly from saidstator those particles having a magnetic susceptibility nearer saidgiven level, deflecting means extending between said liner and oneportion of said housing for deflecting said material having a relativelyhigh magnetic susceptibility from said rotating field, said means beinglocated at an angular position with respect to said liner which isspaced from the location at which the material is introduced into saidfield, means for removing from said housing the material that isseparated by centrifugal force from said field after reaching asufficient angular velocity, means for removing from said housing thematerial that is separated by said deflecting means, and means forremoving from said housing the material having a magnetic susceptibilitybelow said given level.

III

UNITED STATES PATENT oFFicE CERTIFICATE OF CORRECTION Patent No. 3,68LLO90 Dated August 15, 1972 Inventor(s) James R. Kilbride It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column l,--line 67, "middling" should be middlings.

Column 3, line '59., "of" (second occurrence) should be --or--; line 60,"resistance" should be -resistant-- Column l, line 58, "direction"should be --location. Column5, line 60, "other" should be -order-.Column 6,'line 30, "A" should be --a--. Column 7, line #5, after "58insert -therewith. Depending upon the field strength, the middlings 58line 60, "The" should be -the-. Column 9, line 20, "Claim 12" should beClaim lO-; line 23, "outwardly" should be -upwardly-.

Signed and sealed this 9th day of January 1973..

(SEAL) Attest:

EDWARD MJ LE'ICI-IERJR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents FORM PO-1OSO (10-69) USCOMM-DC 60376-P69 a u sv GOVERNMENTPRINTING bFFIcE I969 0-365-331

1. A method of separating material composed of particles having severaldifferent magnetic susceptibilities, said material including firstparticles having a magnetic susceptibility below a given level, andsecond and third particles having magnetic susceptibilities above saidlevel, said third particles having a higher susceptibility than saidsecond particles, the method comprising the steps of producing arotating magnetic field of uniform strength, introducing the material tobe separated into the field at first location so that the firstparticles having a magnetic susceptibility below said given level flowgravitationally downwardly and said second and third particles having asusceptibility above said given level are accelerated entirely by saidfield to the extent that the second particles possessing a magneticsusceptibility nearer said given level are thrown outwardly due tocentrifugal force developed solely by said rotating field and arethereby separated from the third particles having a highersusceptibility, and removing said higher susceptibility third particlesfrom said field at a second location prior to the completion of a fullrevolution of said rotating field and prior to reaching said firstlocation where the material to be separated is introduced, whereby saidfirst particles are initially separated by gravity from said second andthird particles, and said second particles are subsequentlycentrifugally separated from said third particles at a third locationbetween said first and second locations.
 2. The method set forth inclaim 1 in which said field rotates about a substantially horizontalaxis.
 3. The method set forth in claim 2 in which said first location atwhich the material is introduced is spaced from said axis in a generallyhorizontal direction.
 4. The method set forth in claim 3 in which saidfirst location is disposed where the field is moving upwardly and saidthird particles having a higher magnetic susceptibility are removed at alocation spaced angularly approximately 270* from said first location.5. The method set forth in claim 3 in which said first location isdisposed where the field is moving downwardly and said third particleshaving a higher magnetic susceptibility are removed at a location spacedapproximately 360* from said first location.
 6. The method set forth inclaim 1 in which said field rotates about a substantially vertical axis.7. The methods set forth in claim 6 in which said first location isdisposed radially outward from said axis and at an elevation above themiddle of said axis.
 8. The method set forth in claim 1 in which thelocation for removing said first particles having a lesser magneticsusceptibility is beneath said first location.
 9. Apparatus Forseparating material composed of particles having different magneticsusceptibilities comprising a stator including a stationary non-magneticshell having a generally cylindrical outer surface and a generallycylindrical inner surface and a plurality of polyphase windings fixedlydisposed within said shell in an adjacent relationship with the saidinner surface thereof, said windings generating a rotatingelectromagnetic field that progresses circumferentially therearound,means for introducing said material into said field at one radiallocation so that particles having a magnetic susceptibility less than agiven level fall gravitationally out of said field and the particleshaving a magnetic susceptibility above said given level are acceleratedexclusively by said field to the extent that those particles possessinga magnetic susceptibility nearer said given level are thrown outwardlyaway from the outer surface of said shell due solely to centrifugalforce developed only by said rotating field and thereby separated fromthose particles having a higher susceptibility which continue in aproximal relationship to said outer surface due to said rotating field,means for collecting said centrifugally separated particles so that theyremain separated from those particles having a higher susceptibility sothat said higher susceptibility particles continue in said proximalrelationship to said outer surface, and means extending outwardly fromthe outer surface of said shell at a location less than 360* from saidone location for deflecting those particles having a highersusceptibility which have continued along said outer surface from saidfield prior to the completion of a full revolution of said field. 10.The apparatus set forth in claim 9 in which said stator is disposedalong a substantially horizontal axis.
 11. The apparatus set forth inclaim 12 including means having an inlet opening disposed generallyhorizontally at said one location where the electromagnetic field ismoving outwardly, and means located generally beneath said stator viawhich those particles having a magnetic susceptibility less than saidgiven level are gravitationally removed.
 12. The apparatus set forth inclaim 11 in which said means for deflecting said higher susceptibilityparticles from said field includes a barrier extending angularly fromsaid stator, said means for gravitationally removing these particleshaving a magnetic susceptibility less than said given level being to oneside of said barrier, and means to the other side of said barrier forremoving the particles having the highest magnetic susceptibility afterbeing deflected by said barrier.
 13. The apparatus set forth in claim 12including an adjustable splitter vane for determining the crosssectional area through which the highest magnetic susceptibilityparticles pass and thereby the amount thereof.
 14. The apparatus setforth in claim 10 including means having an inlet opening disposedgenerally at said one location where the electromagnetic field is movingdownwardly, and means located generally beneath said stator via whichthose particles having a magnetic susceptibility less than said givenlevel are gravitationally removed.
 15. The apparatus set forth in claim14 in which said means for deflecting said high susceptibility particlesfrom said field includes a barrier extending angularly from said statorimmediately above said one location, and an adjustable splitter vanebeneath said stator for determining the cross sectional area throughwhich the particles above said given level of susceptibility pass andthereby the amount thereof.
 16. The apparatus set forth in claim 15 inwhich said means for removing those particles having a magneticsusceptibility less than said given level is to one side of saidsplitter vane and said means for collecting said centrifugally separatedparticles is to the other side thereof.
 17. The apparatus set forth inclaim 9 in which said stator is disposed along a subStantially verticalaxis.
 18. The apparatus set forth in claim 17 in which said one locationis adjacent the upper end of said stator.
 19. Apparatus for separatingmaterial composed of particles having different magneticsusceptibilities comprising a housing, a stator including a stationarynon-magnetic shell having a generally cylindrical outer surface and agenerally cylindrical inner surface and a plurality of polyphasewindings fixedly disposed within said shell in an adjacent relationshipwith the inner surface thereof, said shell being arranged horizontallywithin said housing and said windings generating a rotatingelectromagnetic field that progresses circumferentially therearound,means for introducing the material to be separated into said field atone radially located position so that the particles having a magneticsusceptibility below a given level fall gravitationally toward thebottom of said housing and those particles having a magneticsusceptibility above said given level are carried by said rotatingfield, means located at a second radial position spaced angularly fromsaid first position for deflecting the material having a high magneticsusceptibility out of said field, first means for collecting thematerial having a magnetic susceptibility nearer said given level whichis thrown outwardly away from the outer surface of said shell bycentrifugal force developed solely from said rotating field, and secondmeans for collecting the material having said high magneticsusceptibility deflected by said deflecting means after said materialhaving a magnetic susceptibility nearer said given level has been thrownoutwardly away from said outer surface due to centrifugal force.
 20. Theapparatus set forth in claim 19 including a splitter vane adjustablypositionable with respect to said stator so as to cause more or lessconcentrate to be removed.
 21. The apparatus set forth in claim 20 inwhich said second collecting means includes an outlet in the bottom ofsaid housing via which the material having a relatively high magneticsusceptibility is removed and said first collecting means includes anoutlet in the bottom of said housing via which the material having amagnetic susceptibility nearer said given level is removed, and in whichsaid splitter vane is pivotally mounted about a horizontal axis so thatits upper edge can be swung to a position nearer said stator to divertmore of said material having a magnetic susceptibility nearer said givenlevel into said first collecting means and less of the material having arelatively high magnetic susceptibility into said second collectingmeans.
 22. Apparatus for separating material composed of particleshaving different magnetic susceptibilities comprising a housing having abottom, a stator including a stationary non-magnetic shell having agenerally cylindrical outer surface and a generally cylindrical innersurface fixedly disposed in said housing and a plurality of polyphasewindings fixedly disposed within said shell for generating a rotatingelectromagnetic field, the bottom of said housing having a first outletformed therein located beneath said stator via which non-magneticparticles are gravitationally discharged, means for introducing saidmaterial into said housing at a location adjacent said stator so thatthe material enters the field at a relatively high intensity portionthereof whereby the particles having a magnetic susceptibility above agiven level are accelerated entirely by said field to the extent thatthose particles possessing a magnetic susceptibility nearer said givenlevel are thrown outwardly from the outer surface of said shell due tocentrifugal force developed solely by said rotating field, said bottomhaving a second outlet therein laterally offset from said shell viawhich said centrifugally separated particles are removed, a barrierextending across said housing for deflecting those particles having arelatively high magnetic susceptibility from said field, said barrIerbeing located a substantial angular distance from the location at whichthe material is introduced into said housing, said bottom having a thirdoutlet opening located near said barrier so that material deflectedthereby which has continued in a proximal relation along said outersurface is removed via said outlet.
 23. The apparatus of claim 22including a splitter vane between said second and third outlet fordiverting more of said relatively high magnetic susceptibility materialthrough said third outlet when moved into one position and less of saidrelatively high magnetic susceptibility material when moved into asecond position.
 24. In apparatus for separating materials composed ofparticles having different magnetic susceptibilities, a housing, astator contained in said housing comprising a plurality of stackedlaminations, each lamination having a series of angularly spaced pointedteeth projecting radially outwardly therefrom to form slots between thevarious angularly spaced teeth, a plurality of coils disposed in saidslots, a non magnetic liner encircling the pointed ends of said teeth,whereby polyphase energization of said coils produces a rotating fieldsufficiently intense so as to carry with it particles having a magneticsusceptibility above a given level and which field will produce asufficient amount of centrifugal force to throw outwardly from saidstator those particles having a magnetic susceptibility nearer saidgiven level, deflecting means extending between said liner and oneportion of said housing for deflecting said material having a relativelyhigh magnetic susceptibility from said rotating field, said means beinglocated at an angular position with respect to said liner which isspaced from the location at which the material is introduced into saidfield, means for removing from said housing the material that isseparated by centrifugal force from said field after reaching asufficient angular velocity, means for removing from said housing thematerial that is separated by said deflecting means, and means forremoving from said housing the material having a magnetic susceptibilitybelow said given level.